1. Field of the Invention
The invention relates in general to a packaging substrate and a manufacturing method thereof, and more particularly to a packaging substrate including all good substrate units and a manufacturing method thereof.
2. Description of the Related Art
As developing rapidly and applied to all kinds of electronic products, semiconductor technology brings convenience to everyone's daily life. In the semiconductor packages, inner circuits of the chips are electrically connected to outer circuits through bumps, lead frames or wires. The packages protect the semiconductor chips from collision and moisture. Nowadays, the circuits of the chips become more and more complicated, and the number of electric contacts increases. As a result, the semiconductor packages evolve from dual in line packages (DIP) into packages with dense pins and suitable for high-speed chips, such as ball grid array (BGA) packages. As all kinds of electronic products emerge into the market, the demand for chips increases greatly. Therefore, semiconductor-packaging technology plays a very important role in the industrial development nowadays.
FIG. 1 is a cross-sectional view of a conventional ball grid array package. Please referring to FIG. 1, a package 10 includes a packaging substrate 14, several gold wires 12, a chip 11, a packaging resin 13, several tin balls 15 and a silver adhesive 16. The packaging substrate 14 includes a circuit (not shown in FIG. 1). Several contacts on a lower surface 14b of the packaging substrate 14 are electrically connected to the circuit. The tin balls 15 are adhered to the contacts for electrically connecting the package 10 and an outer electronic device. The chip 11 includes several bonding pads 17. The chip 11 is attached to an upper surface 14a of the packaging substrate 14 through the silver adhesive 16. The bonding pads 17 are electrically connected to the circuit through the gold wires 12. The packaging resin 13 disposed on the packaging substrate 14 covers the gold wires 12 and the chip 11, for physically protecting the gold wires 12 and the chip 11. For example, the resin 13 protects the gold wires 12 and the chip 11 from collision and moisture.
Furthermore, in order to increase the packaging efficiency, a strip substrate is used for packaging several chips at the same time instead of using only one substrate to package one chip at a time. Please referring to FIG. 2, a conventional strip packaging substrate is illustrated in FIG. 2. A strip packaging substrate 20 includes several substrate units 21 arranged linearly. However, not all of the substrate units 21 on the strip packaging substrate 20 are good. Defected substrate units 21 result in defected packages. As a result, the yield rate is decreased. Generally speaking, when the number of defected substrate units 21 of the strip packaging substrate 20 reaches a certain amount, the strip packaging substrate 20 with the defected substrate units 21 and some good substrate units 21 are discarded at the same time. As a result, the good substrate units 21 in the discarded packaging substrate are wasted, so the cost is increased relatively. Therefore, it is very important to ensure that all the substrate units 21 on the strip packaging substrate 20 are good, so that good substrate units 21 can be utilized effectively.